Wafer transport system

ABSTRACT

A substrate transport system includes a substrate cart inside a chamber and a linearly driven shuttle outside the chamber configured to levitate the substrate cart into a non contact, spaced relationship with respect to outwardly opposing sides of an interior wall of the chamber and to linearly drive the substrate cart within the chamber.

RELATED APPLICATIONS

This application claims benefit of and priority to U.S. ProvisionalApplication Ser. Nos. 61/627,065 and 61/627,031 filed Sep. 16, 2011under 35 U.S.C. §§119, 120, 363, 365, and 37 C.F.R. §1.55 and §1.78 andincorporated herein by this reference.

FIELD

The disclosed embodiment relates to wafer and other types of substrateprocesses.

BACKGROUND OF THE INVENTION

Wafers are typically handled in a vacuum environment to preventcontamination of the wafers and resulting electronic chips. Since motorsand the like could result in contamination of the vacuum environment andthe wafers, robot arms and structure used to handle wafers are designedso that all of the motors are outside the vacuum enclosure. See, e.g.,U.S. Pat. No. 6,485,250 incorporated herein by this reference.

To transport wafers and other like substrates amongst differentprocessing modules (e.g., load ports, load locks, transport chambers,processing modules, and the like), wafer carts are used. There have alsobeen efforts to effect magnetic levitation in driving the wafer cart ina vacuum transport chamber.

In some designs, selectively energizeable electromagnets on one or moretracks outside the vacuum chamber interact with permanent magnets on awafer cart inside the vacuum chamber to levitate and drive the wafercart inside the vacuum chamber. See U.S. Pat. No. 4,624,617 incorporatedherein by this reference. Controlling the wafer cart so it doesn't touchthe vacuum chamber walls is difficult. See published U.S. ApplicationNo. 2009/0162179, incorporated herein by this reference. More advanceddesigns are highly complex, expensive, may be unreliable, and utilize asignificant amount of energy. See U.S. Pat. Nos. 6,183,615 and 6,684,794incorporated herein by this reference.

In other systems, a drive unit outside the vacuum has permanent magnetsand so too does the wafer shuttle inside the vacuum chamber. See U.S.Pat. Nos. 7,841,820 and 4,805,761 incorporated herein by this reference.But, permanent magnet based systems necessarily results in a wafershuttle which must contact the vacuum chamber walls. Contamination ofthe vacuum chamber and thus the wafers processed therein is thuspossible through friction and wear of the contact surfaces.

SUMMARY

In one aspect, the wafer cart need not touch the vacuum chamber wallsand yet the system is less complex and less expensive than priorsystems. One unique aspect associated with one preferred embodimentfeatures a vacuum chamber with a shape defining an interior rail for thewafer cart and an exterior tunnel for the shuttle. A portion of thewafer cart conforms to the vacuum chamber interior rail.

This invention features a substrate transport system comprising achamber, a substrate cart inside the chamber, and a linearly drivenshuttle outside the chamber. The linearly driven shuttle is configuredto levitate the substrate cart into a non contact spaced relationshipwith respect to outwardly opposing sides of an interior wall of thechamber and to linearly drive the substrate cart within the chamber.

The substrate transport system could be a linearly driven shuttle whichis driven by a lead screw coupled to the chamber or the shuttle mayinclude a motor. The chamber wall could be a tunnel and with thesubstrate cart on opposing sides of the tunnel. A second substrate cartcan be disposed on a common path with respect to the first substratecart and linearly movable independent of the first substrate cart.

The linearly driven shuttle could have a magnetic subsystem with anactive suspension portion and a passive coupling portion. The activesuspension portion actively levitates the substrate cart into a noncontact spaced relationship with respect to the interior wall of thevacuum chamber and the passive coupling portion is configured topassively linearly drive the substrate cart within the vacuum chamber.This embodiment of the substrate cart may comprise spaced ferromagneticmembers.

Also featured is a substrate transport system comprising a substratecart inside a vacuum chamber and a linearly driven shuttle outside thevacuum chamber configured to actively levitate the substrate cart into anon contact spaced relationship with respect to outwardly opposing sidesof an interior wall of the vacuum chamber. The linearly driven shuttleis magnetically coupled to the substrate cart and is configured tolinearly drive the substrate cart within the vacuum chamber. An interiorwall forms a vacuum barrier between the linearly driven shuttle andinside the vacuum chamber. The linearly driven shuttle may be driven bya lead screw coupled to the chamber.

Also featured is a substrate transport system including a substrate cartinside a vacuum chamber, a linearly driven shuttle outside the vacuumchamber and linearly moveable with respect to the vacuum chamber. Thelinearly driven shuttle includes a magnetic subsystem with an activesuspension portion and a passive coupling portion. The active suspensionportion is configured to actively levitate the substrate cart into a noncontact spaced relationship with respect to outwardly opposing sides ofan interior wall of the vacuum chamber. The linearly driven shuttle isalso passively magnetically coupled to a substrate cart with the passivecoupling portion configured to passively linearly drive the substratecart within the vacuum chamber. The interior wall may form a vacuumbarrier between the linearly driven shuttle and inside the vacuumchamber.

The disclosed embodiments need not achieve all these objectives and theclaims hereof should not be limited to structures or methods capable ofachieving these objectives.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objects, features and advantages will occur to those skilled inthe art from the following description of a preferred embodiment and theaccompanying drawings, in which:

FIG. 1 is a schematic top view of a simplified example of a waferprocessing system including various modules;

FIG. 2 is a schematic view showing the rail and tunnel portion of thevacuum chamber transport module depicted in FIG. 1;

FIG. 3 is a schematic three dimensional view showing now the wafer cartinside the vacuum chamber about its rail and a linearly driven shuttlemaneuverable in the tunnel defined by the vacuum chamber;

FIG. 4 is a schematic three dimensional front view of the wafer cartshown in FIG. 3;

FIG. 5 is a schematic three dimensional partially cut away view of anexample of a linearly driven shuttle as depicted in FIG. 3;

FIG. 6 is a block diagram showing the primary components associated withthe linearly driven shuttle as depicted in FIG. 5;

FIG. 7 is a highly pictorial view of the wafer cart and the shuttledepicted in FIGS. 4 and 5 showing the passive and active magneticcoupling techniques used in one preferred embodiment of the invention;

FIG. 8 is a schematic cross sectional depiction of another vacuumchamber featuring two wafer carts and two shuttles;

FIGS. 9A and 9B are schematic top views showing another example of awafer transport system in accordance with the invention;

FIG. 10 is a schematic cross sectional view of a magnetic ball screw andmagnetic array configured as a nut associated with the system of FIG. 9;

FIG. 11 is a schematic cross sectional front view of an example of asubstrate transport platform in accordance with one embodiment;

FIGS. 12A and 12B are schematic views showing examples of differenttypes of vacuum chamber configurations;

FIG. 13 is a schematic top view showing another example of a substratetransport system;

FIG. 14 is a schematic cross sectional view showing an example of amagnetic array fashioned as a wheel in accordance with the example ofFIG. 13; and

FIGS. 15A and 15B are schematic top views showing the operation of thesystem of FIGS. 13 and 14.

DETAILED DESCRIPTION

The disclosed embodiment is capable of other embodiments and of beingpracticed or being carried out in various ways. Thus, it is to beunderstood that the disclosed embodiment is not limited in itsapplication to the details of construction and the arrangements ofcomponents set forth in the following description or illustrated in thedrawings. If only one embodiment is described herein, the claims hereofare not to be limited to that embodiment. Moreover, the claims hereofare not to be read restrictively unless there is clear and convincingevidence manifesting a certain exclusion, restriction, or disclaimer.

FIG. 1 depicts an example of wafer processing modules 12 a and 12 b,transport module 14, and load station 16, all of which typicallyconstitute interconnected vacuum chambers. In this simplified example,processing chambers 12 a and 12 b may include robot arms. There may bemany more modules and stations in a complete system.

FIG. 2 shows one particular vacuum chamber 14 defining exterior tunnel20 forming interior rail 22. Wafer cart 24, FIG. 3 is disposed insidevacuum chamber 14 and is configured with shoe 26 shaped about vacuumchamber rail 22. In this specific example, rail 22 is a curved convexstructure and shoe 26 is a curved concave structure. Shuttle 30levitates cart 24 into a non-contact spaced relationship with respect tointerior wall 22 of chamber 14 and linearly drives shuttle 24 withinchamber 14.

Shuttle 30 is preferably linearly driven and resides outside vacuumchamber 14 and travels to and fro in tunnel 20. Shuttle 30 and wafercart 24 are configured such that wafer cart 24 is levitate by shuttle 30(shoe 26 is spaced from rail 22) and follows shuttle 30 as it travels intunnel 20.

In this way, a wafer or other like substrate on supports 32 a-32 d onthe top surface of wafer cart 24 can be transported, for example, fromload lock 16, FIG. 1 to station 12 b via vacuum chamber 14. In otherexamples, wafer cart 24 is equipped with one or more movable maneuveringwafer arms. See, for example, U.S. Pat. No. 7,901,539 incorporatedherein by this reference.

In one preferred design as shown in FIGS. 3-4, the wafer cart shoe walls32 a, 32 b; the tunnel walls 34 a, 34 b; and optionally the shuttlewalls 36 a, 36 b are configured in a concentric design as shown so, forexample, shuttle wall 36 a is fairly close to and shaped the same aswafer cart wall 32 a and yet separated therefrom by vacuum chamberbarrier wall 34 a.

Now, with electromagnetic and permanent magnets in the shuttle walls andferromagnetic material in the wafer cart walls, the wafer cart can beelevated within the vacuum chamber slightly above rail 22 and driven toand fro in vacuum chamber 14, and also controlled so that the shuttledoes not touch the vacuum chamber.

For example, here shuttle wall 36 is made of non-magnetic material suchas stainless steel. Set in shuttle wall 36 b are fore and aftelectromagnets 40 a and 40 b and permanent magnet 42 a. Shuttle wall 36a is configured similarly. Non-magnetic wafer cart wall 32 a has spacedferromagnetic (e.g., iron) members 50 a, 50 b, 50 c as does wall 32 b.

Shuttle permanent magnets 42 a and wafer cart ferromagnetic member 50 bare configured to levitate the wafer cart off the vacuum chamber railand to urge the wafer cart to follow the shuttle.

To control the orientation of the wafer cart, the electromagnets areused in conjunction with the ferromagnetic elements in the wafer cartwalls. For example, if the left hand side of the wafer cart (e.g., wall32 a) starts to get too close to rail 22 (and wall 34 a) as determinedby position sensors, then both electromagnets 40 a and 40 b areenergized, pulling wall 32 b of the wafer cart closer to vacuum chamberwall 34 b and driving wafer cart wall 32 a away from vacuum chamber wall22 and also centering the wafer cart in a spaced relationship withrespect to the vacuum chamber rail. Energizing only one shuttleelectromagnet (or alternate side, different position electromagnets)would change the yaw angle of the wafer cart.

In this way, with only four electromagnets and two permanent magnets,the wafer cart yaw, pitch, and roll can be controlled. For example, ifthe wafer cart is pitched down in the front, rear shuttle electromagnets40 a can be energized. If the wafer cart rolls to the right, left handside electromagnets can be energized to correct the roll.

And, the wafer cart is designed to remain sterile. Shuttle 30, FIG. 5contains the linear drive mechanism(s), the position sensors, the drivenmagnetic coils, the power supply, the controlling electronics and thelike but shuttle 30 is outside of the vacuum chamber. One exemplarydrive mechanism 59 includes belt 60 fixed on one or both ends and drivenby motor drive 62 between free spinning pulleys 64 a and 64 b. Otherdrive mechanisms are possible.

Another drive mechanism for shuttle 30 is a lead or ball screwarrangement for a magnetic screw. See, for example, U.S. Pat. No.6,712,907 incorporated herein by this reference.

Shuttle 30, FIG. 6 includes a drive subsystem 59 as just disclosed,power supply 70, an electromagnetic subsystem 72, a sensor subsystem 74,and controller 76. Controller 76 (e.g., a microcontroller, applicationspecific integrated circuit, or the like), based on the output of sensorsubsystem 74, controls both drive subsystem 59 and, as discussed above,the electromagnetic subsystem 72 to control the orientation of the wafercart with respect to the vacuum chamber rail. Control and positioning ofthe vacuum wafer cart based on position sensors and electromagnets isnoted in published U.S. Application No. 2009/0162179, incorporatedherein by this reference.

FIG. 7 shows again wafer cart 24 and shuttle 30 and the respectivepermanent magnets (42), electromagnets (40) and ferromagnetic members(50). The interaction between the shuttle electromagnetics and the wafercart ferromagnetic members is active coupling while the interactionbetween the shuttle permanent magnets and the wafer cart ferromagneticmembers is passive coupling as depicted in the figure. The vectors shownshow how active control F_(LFy) and F_(RFy) control y_(F) and F_(LFy)and F_(RRy) control y_(R) for guidance and yaw control. Passive couplingmeans F_(Lx) and F_(Rx) control x for propulsion and R_(LFz), F_(RFz),F_(LRz), and F_(RRz) control z and Ry for lift, pitch, and roll control.

FIG. 8 shows a dual shuttle configuration where vacuum chamber 14includes two independently driven substrate carts 24 a and 24 b eachwith conforming shoes 26 a and 26 b. Vacuum chamber 14 defines dualrails 22 a and 22 b and two independently driven shuttles 30 a and 30 bare shown. Wafer cart 24 a supports substrate 80 b on top surface 82 a aportion of which extends over wafer cart 24 b as shown. Wafer cart 24 bsupports wafer 80 b on top surface 82 b which extends horizontally fromvertically disposed arm 86. Cutouts such as cutout 90 is for weightsavings and/or balance control.

The result is one or more wafer carts that do not touch the vacuumchamber walls and yet the system is less complex and less expensive thanprior systems. In one aspect, irrespective of the specific shape orshapes or configurations, the preferred vacuum chamber forms an interiorrail of a sort with a tunnel in it for travel of the exterior shuttle.The wafer cart inside the vacuum chamber has a shoe portion shapedconformably about the vacuum chamber rail. A magnet subsystem isassociated with at least the shuttle and is configured to levitate thewafer cart conformal shoe into a spaced relationship with respect to thevacuum chamber interior rail, to adjust the orientation of the wafercart with respect to the rail, and to drive the wafer cart in the vacuumchamber with the shuttle outside the vacuum chamber in the tunnel.

In other designs, the shuttle in the tunnel is or includes one or moremagnetic ball screws. FIGS. 9A and 9B show a design with two magneticball screws 110 a and 110 b outside the vacuum environment and magneticarrays configured as nuts 114 a and 114 b within the vacuum environmentmagnetically linearly driven by screws 110 a and 110 b, respectively.See also FIG. 10. The nuts support frame members 102 a and 102 b. InFIG. 9A, driving both screws in the same direction linearly drives framemembers 102 a and 102 b within the vacuum chamber. Driving the screws inthe opposite direction can cause an arm on the frame members to rotate,or the like.

The contactless lead screw mechanism(s) may be utilized to convertrotary motion to linear motion, and vice versa without the negativeaspects of mechanical contact, such as the presence of friction, theneed for lubrication, generation of particles and sensitivity toaggressive environments associated with conventional lead screws andball screws. Therefore, due to its cleanliness of operation, thecontactless lead screw mechanism may be suitable for clean and vacuumapplications and, due to its resistance to aggressive agents, for harshenvironments where conventional solutions fail. The present contactlesslead screw mechanism of one or more embodiments of this invention may beutilized in a material transport system, e.g., to produce linear motionof a material transport platform.

As shown in FIG. 10, the contactless lead screw mechanism may include alead screw component 110 with threads having a thread pitch and one ormore nut components 114 with threads having substantially the samethread pitch as the pitch of the screw. The lead screw component mayinclude a body of a substantially cylindrical shape and thread-typefeatures on the cylindrical body made of a ferromagnetic material. Thethread-type features may be made of a solid piece, assembled frommultiple pieces, laminated from multiple sheets to reduce eddy currentlosses, formed from powder metal or produced in any other suitablemanner. The lead screw component may be constrained so that it isallowed to rotate with respect to the axis of its cylindrical body ortunnel, e.g., by utilizing one or more rotary bearings, with respect tothe nut component(s). Each nut component 114 may include a body, made ofone or more parts, with a substantially hollow cylindrical cavity, whichmay feature a thread-type arrangement made of a ferromagnetic materialand compatible with the thread-type features on the lead screwcomponent. The thread-type arrangement may be made of a solid piece,assembled from multiple pieces, laminated from multiple sheets to reduceeddy current losses, or produced in any other suitable manner. Each nutmay also feature one or more magnets located so that a magnetic circuitis closed through the thread-type arrangement of the nut component andthe thread-type features of the lead screw component. The magnets may bepermanent magnets, electrically activated magnets or any magnets of anysuitable type.

In an alternative embodiment, the magnet(s) of the nut component mayinteract directly with the thread-type features of the lead screwcomponent. In yet another embodiment, the magnet(s) may be incorporatedinto the lead screw component. Each nut component may be constrained sothat it is allowed to translate along the axis of the cylindrical bodyof the lead screw component, e.g., by utilizing one or more linearbearings, with respect to the lead screw component. A separation vacuumchamber wall made of a non-ferromagnetic material, which may, forexample, be of a cylindrical shape, may be present between the ballscrew component and the nut component(s).

When the lead screw component is caused to rotate, the magnetic fieldproduced by the magnets results in magnetic forces between thethread-type features of the lead screw component and the thread-typearrangement of the nut component(s). This causes the nut component(s) tomove linearly along the axis of the cylindrical body of the lead screwcomponent. The separation wall between the lead screw component and thenut component(s) may be utilized to separate the environment where thelead screw component is located from the environment of the nutcomponent(s). For example, the lead screw component may be located inatmosphere and the nut component(s) may be located in vacuum.

Numerous industrial applications, including transportation andpositioning systems, require a platform that can move along astraight-line path while carrying an actively driven mechanism, such asa robotic arm. The moveable platform according to one or moreembodiments of this present invention may provide this functionalitywith no on-board active components, such as power management solutions,control electronics and actuation arrangements. As a result, themoveable platform of this invention may be suitable for applicationswhere the presence of active components on the moveable platform isundesirable, for instance, due to issues with heat removal, such as invacuum environments.

As shown in FIG. 9, the moveable platform according to the oneembodiment of this invention may include a body, which may beconstrained to move along a straight-line path, for example, byutilizing one or more linear bearings or a magnetic levitation system.One or more magnetic nut components may be rigidly or moveably coupledto the body. One or more lead screw components may be arranged along thedirection of motion of the body, for example, on the side of the body,below the body, above the body or in any suitable manner, so that theaxes of rotation of the worm components are substantially parallel withthe direction of motion of the body. Each of the lead screw componentsmay interact with one or more nut components through magnetic forces,forming one or more contactless lead screw mechanisms. Separation wallsmade of a non-ferromagnetic material may be present between the nutcomponent(s) and the lead screw component(s).

An example of the moveable platform of one or more embodiments of thisinvention may include a body with a first nut component attached rigidlyto the body and a second nut component coupled moveably to the body,e.g., through a linear bearing. A first lead screw component may beutilized to interact with the first nut component, and a second leadscrew component may be utilized to interact with the second nutcomponent. When the first and second lead screw components rotate in thesame direction, the first nut causes the body of the platform to moveand the second nut moves with the body in the same manner as the body.If the first lead screw component is kept stationary and the second leadscrew component rotates, the first nut component and, therefore, thebody remain stationary while the second nut component moves relative tothe body. Any combination of translation of the body and relative motionof the second nut component with respect to the body may be achieved byproperly coordinated rotation of the two lead screw components. In thisway, a substrate cart body can be driven linearly and an arm on thesubstrate cart body can be rotated.

The arrangement discussed above may be utilized to realize a moveableplatform that may carry a robotic arm driven by the relative motion ofthe second nut component with respect to the body. When the lead screwcomponents rotate in the same direction, the entire platform translateswith no motion of the robotic arm with respect to the body of theplatform. By rotating the second lead screw component while the firstlead screw component is kept stationary, the robotic arm may be operatedwhile the body of the platform remains stationary. The arm may beoperated simultaneously while the body of the platform moves by properlycoordinated rotation of the two lead screw components. Separation wallsbetween the nut components and the lead screw components may be utilizedto separate the environment(s) where the body and robotic arm operateand where the lead screw components are located. For example, since thebody and robotic arm are completely passive, they may be located in avacuum environment while the lead screw components may conveniently stayin atmosphere. Additional degrees of freedom of the robotic arm may berealized by employing additional nut and lead screw components.

FIG. 11 shows a substrate cart platform 100 with frame 102. Arm 104 a isrotatable with respect frame 102 via linear drive 105 a and bearing 107.Arm 104 h is rotatable with respect to arm 104 a via pulley 108. Arm 104c is rotatable with respect arm 104 b via pulley 109. The cart platformis linearly driven. Thus, here, three degrees of freedom are possible.

Here, there are three ball screw shafts 110 a, 110 b, and 110 c eachindependently driven by a servomotor and belt/pulley set or the like.Each ball screw resides in a tunnel in the vacuum chamber and is thusisolated from the wafer environment.

Rotating ball screw 110 a linearly actuates drive 105 a and rotates arm104 b extending and retracting arms 104 b and 104 c. Rotating all threeball screws 110 a, 110 b, and 110 c linearly moves frames 102 and itsarms. Rotating ball screws 110 a and 110 b rotates arm 104 a.

Linear drive 105 b is linearly activated by rotating ball screw 110 cand linearly actuating drive 105 b rotates pulley 112 which rotates arm104 b. Pulley 112 is rotatable with respect to frame 102 via bearing114. Linear drives 105 a and 105 b may drive their respective arms 104 aand pulley 112 via rack and pinion interfaces, for example.

The linear drives include nuts 114 magnetically driven by theirrespective ball screw shafts. The nuts may include magnetic arrays asshown in and/or as discussed above with respect to FIG. 10 and/or asshown in U.S. Pat. No. 6,712,907 incorporated herein by this reference.Such nuts are within the vacuum environment.

FIG. 12A shows a portion of a vacuum chamber with three non-magneticvacuum barrier sleeves such as tunnels 120 a, 120 b, and 120 c for thethree screw shafts of FIG. 9. FIG. 12B shows an embodiment where twotunnels 120 a′ and 120 b′ are not full tubes.

FIG. 13 shows a design where motors 140 a and 140 b rotate magneticscrew shafts 142 a and 142 b, respectively, in vacuum chamber tunnels120 a and 120 b (see FIG. 10), respectively. Frame 102′ within thevacuum chamber supports one or more arms (see FIG. 9) or serves as awafer cart (see FIG. 3). Magnetic arrays, formed as gears or wheels 150a and 150 b are coupled to frame 102′ and magnetically interact withshafts 142 a and 142 b to rotate and linearly drive frame 102′. See alsoFIG. 14.

This contactless worm drive mechanism may be utilized to transmit rotarymotion, and typically provide speed reduction, from one component toanother component with rotational axes at 90 degrees to each otherwithout the negative aspects of mechanical contact, such as the presenceof friction, the need for lubrication, generation of particles andsensitivity to aggressive environments, associated with conventionalworm drives. Therefore, due to its cleanliness of operation, the presentcontactless worm drive mechanism of one or more embodiments of thisinvention may be suitable for clean and vacuum applications and, due toits resistance to aggressive agents, also for harsh environments whereconventional solutions fail. As an example application, the presentcontactless worm drive mechanism may be utilized in a material transportsystem, for instance, to actuate a material transport platform and itscomponents.

As shown in FIG. 14, the contactless worm drive mechanism of one or moreembodiments of this invention may include a worm component 142 and oneor more warm wheel components 150. The worm component may include a bodyof a substantially cylindrical shape and thread-type features on thecylindrical body made of a ferromagnetic material. The thread-typefeature may be made of a solid piece, assembled from multiple pieces,laminated from multiple sheets to reduce eddy current losses, formedfrom metal powder or produced in any other suitable manner. The wormcomponent may be constrained so that it is allowed to rotate withrespect to the axis of its cylindrical body, for instance, by utilizingone or more rotary bearings, with respect to the worm wheelcomponent(s). Each worm wheel component may include a substantiallycylindrical body, which may feature tooth-type arrangements made of aferromagnetic material and may be geometrically compatible with thethread-type features on the worm component. The tooth-type arrangementsmay be made of a solid piece, assembled from multiple pieces, laminatedfrom multiple sheets to reduce eddy current losses, or produced in anyother suitable manner. Each worm wheel component may also feature one ormore magnets located so that a magnetic circuit is closed through thetooth-type arrangements of the worm wheel component and the thread-typefeatures of the worm component. The magnets may be permanent magnets,electrically activated magnets or other magnets of any suitable type. Inan alternative embodiment of this invention, the magnet(s) of the wormwheel component may interact directly with the thread-type features ofthe worm component. In yet another embodiment, the magnet(s) may beincorporated into the worm component. Each worm wheel component may beconstrained so that it is allowed to rotate with respect to an axisperpendicular to the axis of the cylindrical body of the worm component,for instance, by utilizing one or more rotary bearings, with respect tothe worm component. A separation wall made of a non-ferromagneticmaterial, which may, for example, be of a cylindrical shape, may bepresent between the worm component and the worm wheel component(s).

When the worm screw component is caused to rotate, the magnetic fieldproduced by the magnets results in magnetic forces between thethread-type features of the worm component and the tooth-typearrangements of the worm wheel component(s), causing the worm wheelcomponent(s) to rotate, typically at a reduced speed, allowing forhigher torque. The separation wall 120 between the worm component andthe worm wheel component(s) may be utilized to separate the environmentwhere the worm component is located from the environment of the wormwheel component(s). For example, the worm component may be in atmosphereand the worm wheel component(s) in vacuum.

Numerous industrial applications, including transportation andpositioning systems, may require a platform that can move along astraight-line path while carrying an actively driven mechanism, such asa robotic arm. The moveable platform 102′, FIGS. 15A and 15B may providethis functionality with no on-board active components, such as powermanagement solutions, control electronics and actuation arrangements. Asa result, the moveable platform may be suitable for applications wherethe presence of active components on the moveable platform isundesirable, for instance, due to issues with heat removal, such as invacuum environments.

The moveable platform may include of a body, which may be constrained tomove along a straight-line path, for example, by utilizing one or morelinear bearings or a magnetic levitation system. One or more magneticworm wheel components 150 a and 150 b may be pivotably coupled to thebody. One or more worm components may be arranged along the direction ofmotion of the body, for example, on the side of the body, below thebody, above the body or in any suitable manner, so that the axes ofrotation of the worm components are substantially parallel with thedirection of motion of the body. Each of the worm components mayinteract with one or more worm wheel components through magnetic forces,forming one or more contactless worm drives. Separation walls made of anon-ferromagnetic material may be present between the worm wheelcomponent(s) and the worm component(s).

As shown in FIG. 15, an exemplary embodiment of a moveable platformaccording to one embodiment of this invention may include a body with asingle worm wheel component and two worm components interacting with theworm wheel component on the opposite sides of the worm wheel component.When the worm components are caused to rotate in the same direction,FIG. 15A the worm wheel component does not rotate and translates alongthe direction of motion of the body of the platform, moving the body ofthe platform in the desired direction of motion. If the direction ofrotation of both worm components is reversed, the body reverses thedirection of motion as well.

When the worm components rotate in opposite directions with respect toeach other, FIG. 15B the center of the worm wheel component and,therefore, the body remain stationary while the worm wheel componentrotates with respect to the body. If the direction of motion of each ofthe worm components is reversed, the rotation of the worm wheelcomponent also reverses. Any combination of translation and rotation ofthe worm wheel component may be achieved by properly coordinatedrotation of the two worm components.

The above described arrangement may be utilized to realize a moveableplatform that may carry a robotic arm driven by the worm wheelcomponent. When the worm components rotate in the same direction, theentire platform translates with no motion of the robotic arm withrespect to the body of the platform. The worm components may be drivento rotate in the opposite directions to operate the robotic arm whilethe body of the platform remains stationary. The arm may be operatedsimultaneously while the body of the platform moves by properlycoordinated rotation of the two worm components. Separation wallsbetween the worm wheel component and the two worm components may beutilized to separate the environment(s) where the body and robotic armoperate and where the worm components are located. For example, sincethe body and robotic arm are completely passive, they may be located ina vacuum environment while the driven worm components may convenientlystay in atmosphere. Additional degrees of freedom of the robotic arm maybe realized by employing additional worm drives.

Although specific features of the invention are shown in some drawingsand not in others, this is for convenience only as each feature may becombined with any or all of the other features in accordance with theinvention. The words “including”, “comprising”, “having”, and “with” asused herein are to be interpreted broadly and comprehensively and arenot limited to any physical interconnection. Moreover, any embodimentsdisclosed in the subject application are not to be taken as the onlypossible embodiments.

In addition, any amendment presented during the prosecution of thepatent application for this patent is not a disclaimer of any claimelement presented in the application as filed: those skilled in the artcannot reasonably be expected to draft a claim that would literallyencompass all possible equivalents, many equivalents will beunforeseeable at the time of the amendment and are beyond a fairinterpretation of what is to be surrendered (if anything), the rationaleunderlying the amendment may bear no more than a tangential relation tomany equivalents, and/or there are many other reasons the applicant cannot be expected to describe certain insubstantial substitutes for anyclaim element amended.

Other embodiments will occur to those skilled in the art and are withinthe following claims.

What is claimed is:
 1. A substrate transport system comprising: a chamber; a substrate cart inside the chamber; a linearly driven shuttle outside the chamber; the linearly driven shuttle including a motor, the motor and the linearly driven shuttle together moveable relative to the chamber and wherein the linearly driven shuttle is driven by the motor, the linearly driven shuttle configured to levitate the substrate cart into a non contact spaced relationship with respect to outwardly opposing sides of an interior wall of the chamber; and the linearly driven shuttle configured to linearly drive the substrate cart within the chamber.
 2. The substrate transport system of claim 1 wherein the linearly driven shuttle is driven by a lead screw coupled to the chamber.
 3. The substrate transport system of claim 1 wherein the wall comprises a tunnel and with the substrate cart disposed on opposing sides of the tunnel.
 4. The substrate transport system of claim 1 wherein the substrate cart comprises a first substrate cart, the substrate transport system further comprising a second substrate cart, the second substrate cart disposed on a common path with respect to the first substrate cart and linearly movable independent of the first substrate cart.
 5. The substrate transport system of claim 1 wherein the linearly driven shuttle has a magnetic subsystem, the magnetic subsystem having an active suspension portion and a passive coupling portion, the active suspension portion configured to actively levitate the substrate cart into a non contact spaced relationship with respect to the interior wall of the vacuum chamber, and the linearly driven shuttle passively magnetically coupled to the substrate cart with the passive coupling portion and configured to passively linearly drive the substrate cart within the vacuum chamber.
 6. The substrate transport system of claim 1 wherein the substrate cart comprises spaced ferromagnetic members.
 7. A substrate transport system comprising: a vacuum chamber; a substrate cart inside the vacuum chamber; a linearly driven shuttle outside the vacuum chamber; the linearly driven shuttle including a motor, the motor and the linearly driven shuttle together moveable relative to the chamber and wherein the linearly driven shuttle is driven by the motor, the linearly driven shuttle configured to actively levitate the substrate cart into a non contact spaced relationship with respect to outwardly opposing sides of an interior wall of the vacuum chamber; and the linearly driven shuttle magnetically coupled to the substrate cart and configured to linearly drive the substrate cart within the vacuum chamber; wherein, the interior wall forms a vacuum barrier between the linearly driven shuttle and inside the vacuum chamber.
 8. The substrate transport system of claim 7 wherein the linearly driven shuttle is driven by a lead screw coupled to the chamber.
 9. The substrate transport system of claim 7 wherein the wall comprises a tunnel and with the substrate cart disposed on opposing sides of the tunnel.
 10. The substrate transport system of claim 7 wherein the substrate cart comprises a first substrate cart, the substrate transport system further comprising a second substrate cart, the second substrate cart disposed on a common path with respect to the first substrate cart and linearly movable independent of the first substrate cart.
 11. The substrate transport system of claim 7 wherein the linearly driven shuttle has a magnetic subsystem, the magnetic subsystem having an active suspension portion and a passive coupling portion, the active suspension portion configured to actively levitate the substrate cart into a non contact spaced relationship with respect to the interior wall of the vacuum chamber, and the linearly driven shuttle passively magnetically coupled to the substrate cart with the passive coupling portion and configured to passively linearly drive the substrate cart within the vacuum chamber.
 12. The substrate transport system of claim 7 wherein the substrate cart comprises spaced ferromagnetic members.
 13. A substrate transport system comprising: a vacuum chamber; a substrate cart inside the vacuum chamber; a linearly driven shuttle outside the vacuum chamber and linearly moveable with respect to the vacuum chamber; the linearly driven shuttle having a magnetic subsystem, the magnetic subsystem having an active suspension portion and a passive coupling portion; the active suspension portion configured to actively levitate the substrate cart into a non contact spaced relationship with respect to outwardly opposing sides of an interior wall of the vacuum chamber; and the linearly driven shuttle passively magnetically coupled to the substrate cart with the passive coupling portion and configured to passively linearly drive the substrate cart within the vacuum chamber; wherein, the interior wall forms a vacuum barrier between the linearly driven shuttle and inside the vacuum chamber.
 14. The substrate transport system of claim 13 wherein the linearly driven shuttle is driven by a lead screw coupled to the chamber.
 15. The substrate transport system of claim 13 wherein the linearly driven shuttle further comprises a motor, the motor and the linearly driven shuttle together moveable relative to the chamber and wherein the linearly driven shuttle is driven by the motor.
 16. The substrate transport system of claim 13 wherein the wall comprises a tunnel and with the substrate cart disposed on opposing sides of the tunnel.
 17. The substrate transport system of claim 13 wherein the substrate cart comprises a first substrate cart, the substrate transport system further comprising a second substrate cart, the second substrate cart disposed on a common path with respect to the first substrate cart and linearly movable independent of the first substrate cart.
 18. The substrate transport system of claim 13 wherein the substrate cart comprises spaced ferromagnetic members. 